Similar species: Brassica juncea and B. nigra are the only two Brassica species in the Chicago Region without leaves that are clasping at the base. Brassica nigra is otherwise similar, but it is more or less hairy and not covered with a waxy coating (glaucous).

Flowering: late May to early October

Habitat and ecology: Introduced from Eurasia. A fairly frequent weed in waste ground and on dumps. Also found on railroad ballast.

There are two reports of this weed and I have specimens from three counties. I have always very much disliked the introduced species of crucifers and have neglected to collect them. If I had appreciated the necessity of collecting these weeds, no doubt my records would be more numerous.